1. Field
The following description relates to an array speaker system, and more particularly, to an apparatus and method for generating sound in which sound output through an array speaker is focused on a particular area by controlling a sound field.
2. Description of the Related Art
An array speaker, which is the combination of a plurality of speakers, can be used to control the direction of reproduced sound or to transmit reproduced sound to a predetermined area. Regarding a speaker array, in general, according to a principle of transmitting sound called “directivity,” a plurality of sound source signals are overlapped using the phase difference between the sound source signals such that the intensity of the signals is increased in a particular direction and thus signals are transmitted in a particular direction. In this regard, a plurality of speakers are placed in particular positions and sound source signals output from the respective speakers are controlled, thereby implementing such a directivity.
In the case of a general array system, a desired frequency beam pattern is obtained using filter values such as gains and delays which are calculated for the desired beam pattern, so a fixed beam pattern is only used.
Recently, a personal sound zone technology has garnered a large amount of interest in which noise pollution can be prevented and sound can be transmitted only to a particular listener without an ear phone or a head set. A personal sound zone is formed using the directivity of sound generated by operating a plurality of acoustic transducers. In order to produce the directivity of sound, a time delay or a particular filter value is applied to each input signal of a plurality of speakers, thereby generating a sound beam. Accordingly, sound can be focused towards a particular direction and position.